N-[2-(Diethylamino)ethyl]-N-(2-{[2-(4-hydroxy-2-oxo-2,3-dihydro-1,3-benzothiazol-7-yl)ethyl]amino}ethyl)-3-[2-(1-naphthyl)ethoxy]propanamide free base and its dihydrobromide and dihydrochloride salts are β2 adrenoceptor agonists and are disclosed in PCT/SE2006/000927 (published as WO 2007/018461, see Examples 7, 15 and 16). These compounds show at least 10-fold selectivity for β2 adrenoceptor over adrenergic α1D, adrenergic β1 and dopamine D2.